Injector for logging or intervention string

ABSTRACT

A well logging- or well intervention string injector includes two adjacent motorized endless chains with gripper elements for bearing against the string. The gripping elements have an engagement packer against the string. The gripping elements run over the back supporting rollers carried by separate back supporting roller brackets. The back supporting roller brackets further bear against an elongated hydrostatic pressure equalizing cushion with hydraulic fluid. The pressure equalizing cushion bears against a back supporting rail.

BACKGROUND FOR THE INVENTION

The present invention relates to an injector for a logging- or intervention string for use in petroleum wells. The string, that is to be injected may be a logging string such as a wire, a plain string by metal or composite material or a coiled tubing, carrying a logging tool or an intervention tool that operates down in the petroleum well.

The injector is located at a lubrication central at a lock-chamber at the top of the well. The logging tool, is placed into the lock-chamber and connected to the logging- or intervention string. The string extends up through the lubrication central to the injector. The logging or intervention string, is fed to, or from a reel at the deck and will not be discussed further here.

The injector comprises two adjacent chains with gripper elements. The two chains with the gripper elements is pressed against the intermediate string supported by rollers that in general is back supported by the two adjacent rails assisted by the springs so that the desired pressure from the gripper elements comes to force.

PRIOR ART AND PROBLEMS RELATED TO THIS

U.S. Pat. No. 6,216,780B1 describes a coiled tubing string injector with two adjacent motorized endless chains with gripper elements for bearing against the coiled-tubing string, wherein the gripper elements have an engagement packer to the string (0), and wherein the gripper elements runs over back supporting rollers at back supporting roller brackets. The back supporting roller brackets bear against an elongated thin rubber beam, a resilient gasket that again bear against a back supporting rail. The elongated thin rubber beam will absorb uneven portions locally, but if the rubber beam is compressed, it will only be locally resilient. The local pressure to the coiled tubing will then increase, the back supporting bracket will move away from the string, with the disadvantages of that the pressure to the direct nearby back supporting roller bracket is reduced, and thus the total hold to the string. One may risk that the coiled tubing is locally deformed. The pressure to the string is local increased where an elevation to the string occurs. It is especially undesirable that the local pressure and then the local mechanical load to a coiled tubing occurs since this may damage the tubing. Thus, one have to operate with a somewhat lower total pressure to the coiled tubing string than what one optimal could have used if there had not been any unevenness to the tubing. That result in that one have to operate with a lower upper limit for the pull or push load to the tubing than what is possible at the maximum. This, to have a limit for unevenness that may cause an excess of the maximum allowable local pressure to the tubing. Such a limitation affects the operational use of the coiled tubing injection by lower max load or shorter logging and intervention depths, both vertically and horizontally.

SHORT SUMMARY OF THE INVENTION

A solution to the problems by the prior art is a well logging- or well intervention string (0) injector comprising two adjacent motorized endless chains (16) with gripper elements (2) for bearing against the string (0),

-   -   wherein the gripping elements (2) have an engagement packer         against the string (0),     -   wherein the gripping elements (2) runs over the back supporting         rollers (3) carried by separate back supporting roller brackets         (4),         characterized in     -   that the back supporting roller brackets(4) bear against an         elongated hydrostatic pressure equalizing cushion (5) with         hydraulic fluid (15),     -   wherein the pressure equalizing cushion (5) further a bears         against a back supporting rail (6).

Advantageous embodiments of the invention are given in the independent patent claims.

ADVANTAGES BY THE INVENTION

Any unevenness, with extension comparable to the gripping elements extension, in the diameter or the surface of the string (0), will immediately be absorbed by the local back supporting bracket (4), moving the back supporting roller (3), and by that, the gripper element a small distance in the direction away from, or towards the string (0), to compensate the unevenness. The change in pressure for the locally disturbed back support roller bracket will be distributed by the hydrostatic pressure equalizing cushion (5) at all the other back supporting roller brackets so that

-   -   a) the unevenness easier will pass     -   b) the pressure against the string (0) will be held more even         local     -   c) the total pressure to the string (0) will be held generally         constant, which may result in an increased total pressure to the         string (0) an by that get a stronger gripping force and thus         higher pull or push load than by prior art, without risking         unevenness in the string (0) to bring along a locally to high         pressure.

The pressure equalizing cushion (5) may be compared in the way of working to a local hydraulic piston placed behind every back support roller, and that the hydraulic cylinder is hydraulic connected to each other so the pressure is distributed. However, the pressure equalizing cushion of the invention is a much simpler component than such hydraulic pistons since it will distribute the hydrostatic pressure immediately in its length direction and further distribute the mechanical load from the back supporting roller bracket via the back supporting rollers and the gripper elements that holds by an even pressure to the string.

The rubber beam of the U.S. Pat. No. 6,216,780B1 is resilient. The pressure equalizing cushion (5), according to the invention, is practically non-resilient. Neither locally, nor as a whole. This comparing to the rubber beam in the known U.S. patent, where one may say that the rubber beam performs a local spring resistance, F=kd, where d is the height of the unevenness that passes. The cushion is only flexible locally, with a global pressure distribution, so that it adapt the pressure to be generally equal for all the road of the back supporting roller brackets, and by that, equal for all the gripper elements. One gain at least two advantages: first one prevent parts of deformation of the coiled tubing when the coiled tubing passes the injector since the local unevenness in the diameter of the coiled tubing are met by a transfer under even pressure locally under the roller. Second, due to the fact that better distributed pressure, without risk of pressure tops, is ensured along the part of the coiled tubing passing through the injector, one may increase the total pressure, and thus the total gripping force to the coiled tubing, resulting in that one may drive the coiled tubing in or out of the well with a higher force. Higher force by injection may give an easier access for the logging or intervention strings to the farther, often deviated drilled parts, of the well.

SHORT FIGURE CAPTION

The invention is illustrated in the attached figures and sketches.

FIG. 1 shows a vertical cross section through the injector by to endless chains opposite directed and gripping and driving a vertically running string, for instance a wire, a cable, a straight rod or a coiled tubing.

FIG. 2 shows an enlarged detail with an upper portion of the same injector comprising the upper guiding reels, cogged driving gear and synchronizing gear for the two chains, and an upper portion of the rail and roller system that presses the chains gripper elements towards each side of the string.

FIG. 3 shows an even more enlarged detail of the same wherein generally an upper portion of the rail- and roller system is shown, and where the hydrostatic pressure equalizing cushion upper portion is clearly shown between the separate back support roller brackets and the continuous resilient rigid back supporting rail.

FIG. 4 is a perspective view and a horizontal cross section through the same and illustrates an embodiment wherein the adjacent back supporting rails are coupled up against each other by through bolts and tensioned by springs.

FIG. 5 a illustrates in another perspective that the back supporting reels are supported in back supporting roller brackets, which bear against the pressure equalizing cushion with hydraulic incompressible fluid, which again bear against the resilient back supporting rail. The compassed detail illustrates an enlarged detail around the brackets flange and the pressure equalizer back- and side edge against the back supporting rail.

FIG. 5 b illustrates a section cut of a somewhat different embodiment of the brackets flange and pressure equalizer back- and side edge to the back supporting rail, and that a certain gap is needed to allow movement of the back supporting roller bracket compared to the back supporting rail.

EMBODIMENTS OF THE INVENTION

The invention is a well logging- or well intervention string (0) injector, with two adjacent motorized endless chains (16), with gripper elements (2) for bearing against the string (0), wherein the gripper elements(2) have an engagement packer to the string (0), wherein the gripper elements (2) runs over back supporting rollers (3), carried by separate back supporting roller brackets (4), please see FIG. 1, FIG. 2, and FIG. 3. Novel by the invention is that the back supporting roller brackets (4) further bears against an elongated hydrostatic pressure equalizing cushion (5) with hydraulic fluid (15). The pressure equalizing cushion (5) further bears against a back supporting rail (6). This are shown in FIG. 4 and FIG. 5 a as well. The back supporting rail is generally rigid and straight.

In the Injector according to the invention the back supporting rail (6) is forced in the direction towards the string (0), back supported by two or more springs (12). According to an embodiment of this it is arranged two adjacent back supporting rails mutual forced against each other by the springs (12). In an embodiment shown in FIG. 2, the springs are arranged at the resilient through bolts (13) that extends between the two adjacent back supporting rails. The back support rail may be mounted in pairs as on movable unit which is floating supported by sliding rods in sleeves (14) in the rigid support frame (7) at the outside of the back support rail at each side of the string (0).

The force from a row (16) of gripper elements (2) against the string (0) may in the shown embodiment be adjusted to a larger degree by tightening or loosening the spring bolt (13), or by replacing the spring (12). This has to be carried out at the same time for the whole back supporting rail. Alternatively, one may adjust the hydraulic pressure via a valve (52, 51) in the pressure equalizing cushion (5), se FIG. 3, for minor adjustments in the force from the gripper elements (2).

Every gripper element (2) is in the shown embodiment, se FIG. 4, arranged with lugs with a shaft extending into the driving chain (8). Then each gripper element driven directly by the driving chain (8).

In an embodiment of the invention, the pressure equalizing cushion (5) comprises a flexible metallic house. The flexible metallic house has, in an embodiment illustrated in the attached figures, see FIG. 4 and Fig. especially FIG. 5 a, a rectangular cross section wherein the one flat facing bear against the back supporting rail (6) and where the opposite flat facing bear against under the row of back supporting roller brackets (4). FIG. 5 a shows an embodiment wherein the back supporting rail (6) has a rectangular open channel for the hydrostatic pressure equalizing cushion (5), formed between the two parallel side mouldings (62). The side mouldings (62) constitutes the side walls in the open channel, with the pressure equalizing cushion in the bottom, and that holds the side flanges (41) of a row of back supporting roller brackets (4) in place, so that they do not move broadwise. A locking rail (61) mounted at each side rail (62), holds the side flange (41) in place in the open channel. It is necessary with a certain free motion, i.e. a small gap (63), see the detail in FIG. 5 a or 5 b, at each side of the row between the back supporting roller bracket side flange (41) and the locking rail (61). During operation, the back supporting roller brackets (4) may further move the short extra way in the direction between the back support rail (6) and orthogonal, to the running string (0), so the pressure distribution of the hydrostatic pressure equalizing cushion (5) will work, otherwise the construction will become absolute rigid.

The rear facing of every back supporting roller bracket (4) that faces toward the pressure equalizing cushion (5) are chamfered or rounded by the edges, especially where a back supporting roller bracket meets the next, please see FIG. 3. Further the gnawing to the pressure equalizing cushion (5) is reduced or avoided. The pressure equalizing cushion is in an embodiment made in a flexible metal, for instance steel. In an embodiment the rear facing of the back supporting roller bracket is surface finished by a metal alloy, for instance bronze, to reduce the friction to the pressure equalizing cushion.

The back supporting roller (3) is in the shown embodiment arranged at roller shafts (31) in pairs of side members (42) at the back supporting roller bracket (4). The back supporting roller (3) rotates at a roller axle bearing (32) at a roller axle (31). In this shown embodiment, a roller axle is then static arranged in the side member. In the illustrated embodiment in FIGS. 5 a and 5 b the roller axle is arranged with a central lubrication funnel with openings to lubrication oil to the roller bearings. The lubrication funnel is arranged with a small cylindrical chamber for the lubrication oil in the one side of the roller axle and with a nipple that seals the chamber. In FIG. 5 b it is shown a feed line to a common feed line for lubrication oil so all the axles may be lubricated simultaneously.

In an embodiment of the invention, the pressure equalizing cushion (5) is arranged with sealed ends. In an embodiment the pressure equalizing cushion (5) comprises an inlet valve for hydraulic fluid (15). In an embodiment of the invention a the pressure equalizing cushion (5) is arranged with a ventilation valve (51), See FIG. 3 for drainage of potential gas from the hydraulic fluid (15) so one may avoid heat generation or undesired accumulation of gas over time, which is compressible, in the top of the hydrostatic pressure equalizing cushion. An accumulation of compressible gas, which will be springy, will be detrimental to the hydrostatic balance of the one more of the back supporting roller brackets in the affected upper portion near the undesired accumulation of gas. The pressure equalizing cushion (5) may also be arranged with a valve (52) for system filling of the hydraulic fluid. The fill valve (52) may, in an embodiment, be constituted by the vent valve (51). As described above the clamping pressure against the string (0) may be adjusted somewhat up or down by the valve (51, 52), and a permanent hydraulic line to the valve (51, 52) may be arranged, which also may be used for measuring the hydraulic pressure in the cushion. 

1. A well logging- or well intervention string injector comprising two adjacent motorized endless chains with gripper elements for bearing against said string, wherein said gripping elements have an engagement packer against said string, wherein said gripping elements run over back supporting rollers carried by separate back supporting roller brackets, wherein said back supporting roller brackets further bear against an elongated hydrostatic pressure equalizing cushion with hydraulic fluid, and wherein further said pressure equalizing cushion bears against a back supporting rail.
 2. The injector according to claim 1, wherein said back supporting rail presses in the direction towards said string back supported by two or more springs.
 3. The injector according to claim 2, wherein two adjacent back supporting rails are arranged and mutual forced against each other by springs.
 4. The injector according to claim 1, wherein said pressure equalizing cushion comprises a flexible metallic hose.
 5. The injector according to claim 1, wherein the cross section of said pressure equalizing cushion is rectangular.
 6. The injector according to claim 1, wherein said pressure equalizing cushion has sealing ends.
 7. The injector according to claim 1, wherein said pressure equalizing cushion comprises a valve for supply of hydraulic fluid.
 8. The injector according to claim 1, wherein said pressure equalizing cushion comprises a ventilation valve to drain possible gas from said hydraulic fluid.
 9. The injector according to claim 2, wherein said pressure equalizing cushion comprises a flexible metallic hose.
 10. The injector according to claim 3, wherein said pressure equalizing cushion comprises a flexible metallic hose.
 11. The injector according to claim 2, wherein the cross section of said pressure equalizing cushion is rectangular.
 12. The injector according to claim 3, wherein the cross section of said pressure equalizing cushion is rectangular.
 13. The injector according to claim 4, wherein the cross section of said pressure equalizing cushion is rectangular.
 14. The injector according to claim 2, wherein said pressure equalizing cushion has sealing ends.
 15. The injector according to claim 3, wherein said pressure equalizing cushion has sealing ends.
 16. The injector according to claim 4, wherein said pressure equalizing cushion has sealing ends.
 17. The injector according to claim 5, wherein said pressure equalizing cushion has sealing ends.
 18. The injector according to claim 2, wherein said pressure equalizing cushion comprises a valve for supply of hydraulic fluid.
 19. The injector according to claim 3, wherein said pressure equalizing cushion comprises a valve for supply of hydraulic fluid.
 20. The injector according to claim 4, wherein said pressure equalizing cushion comprises a valve for supply of hydraulic fluid. 